(defvar *db* nil)

(defun make-cd (title artist rating ripped)
  (list :title title :artist artist :rating rating :ripped ripped))

(defun add-record (cd) (push cd *db*))

(defun dump-db ()
  (dolist (cd *db*)
	(format t "~{~a: ~10t~a~%~}~%" cd)))


(defun prompt-read (prompt)
  (format *query-io* "~a: " prompt)
  (force-output *query-io*)
  (read-line *query-io*))


(defun prompt-for-cd ()
  (make-cd
   (prompt-read "Title")
   (prompt-read "Artist")
   (or (parse-integer (prompt-read "Rating") :junk-allowed t) 0)
   (y-or-n-p "Ripped [y/n]")))

(defun add-cds ()
  (loop (add-record (prompt-for-cd))
	 (if (not (y-or-n-p "Another? [y/n]: "))
		 (return))))

(defun save-db (filename)
  (with-open-file (out filename
					   :direction :output
					   :if-exists :supersede)
	(with-standard-io-syntax
	  (print *db* out))))
			

(defun load-db (filename)
  (with-open-file (in filename)
	(with-standard-io-syntax
	  (setf *db* (read in)))))

(defun select (select-fn)
  (remove-if-not select-fn *db*))

(defun artist-selector (artist)
  #'(lambda (cd) (equal (getf cd :artist) artist)))


(defun where (&key title artist rating (ripped nil ripped-p))
  #'(lambda (cd)
			 (and
			  (if title (equal (getf cd :title) title) t)
			  (if artist (equal (getf cd :artist) artist) t)
			  (if rating (equal (getf cd :rating) rating) t)
			  (if ripped-p (equal (getf cd :ripped) ripped) t))))



(defun update (selector-fn &key title artist rating (ripped nil ripped-p))
  (setf *db*
		(mapcar
		 #'(lambda (row)
			 (when (funcall selector-fn row)
			   (if title (setf (getf row :title) title))
			   (if artist (setf (getf row :artist) artist))
			   (if rating (setf (getf row :rating) rating))
			   (if ripped-p (setf (getf row :ripped) ripped)))
			 row)
		 *db*)))

(defun delete-rows (selector-fn)
  (setf *db* (remove-if selector-fn *db*)))


























(defun make-comparison-expr (field value)
  `(list equal (list getf cd ,field) ,value))
